1. Field of the Invention
The present invention relates to a head suspension for a disk drive incorporated in an information processing unit such as a personal computer.
2. Description of the Related Art
A head suspension (hereinafter referred to also as xe2x80x9csuspensionxe2x80x9d) for a disk drive has a base plate and a load beam welded to an end of the base plate. The base plate is used to attach the suspension to a carriage arm of the disk drive. In the disk drive, the suspension is arranged in a space between the carriage arm and a disk. The suspension has a certain height that hinders the miniaturization of the disk drive.
To reduce the height of the suspension, Japanese Patent No. 3089360 discloses a suspension 101 shown in FIGS. 1 and 2. The suspension 101 has a long base plate 103 and a load beam 105 welded to the long base plate 103. The long base plate 103 has a pivot hole 107, which is correctly fitted to a carriage in a disk drive. This prior art uses the long base plate 103 as a carriage arm, to reduce a space between adjacent disks 109 and miniaturize the disk drive.
This prior art, however, has some problems. The flatness of the long base plate 103 is deteriorated when the pivot hole 107 is directly formed through the long base plate 103. The long base plate 103 must secure rigidity because it must serve as a carriage arm. To secure the rigidity, the long base plate 103 has a specified thickness. If the pivot hole 107 is formed through the long base plate 103 by etching, the accuracy of the pivot hole 107 will be low due to the thickness of the long base plate 103. Accordingly, the long base plate 103 with the pivot hole 107 must be formed by press.
The holing by press leaves residual deformation on the long base plate 103, to deteriorate the flatness of the long base plate 103.
An object of the present invention is to provide a head suspension for a disk drive, capable of having precise pivot holes and flatness.
In order to accomplish the object, a first aspect of the present invention provides a head suspension for a disk drive, having support plate means fitted to and supported by a support of a carriage in the disk drive, the support plate means serving as a carriage arm of the carriage, and a load beam resiliently supported by the support plate means and having at least a rigid part, for applying load onto a slider of a head. The first aspect is characterized in that the support plate means is at least made of layered first and second plates, at least the first plate has a thickness appropriate for forming precision holes therethrough by etching, a pivot hole to be fitted to the support of the carriage is formed through the first plate, and one of a pivot hole and a loose hole is formed through the second plate, the pivot hole being equal to and concentric with the pivot hole of the first plate, the loose hole being larger than and substantially concentric with the pivot hole of the first plate.
The first aspect forms the support plate means at least with layered two plates. At least a first plate of the layered structure is provided with a thickness appropriate for forming precision holes therethrough by etching, and a pivot hole is formed through the first plate by etching. This pivot hole is, therefore, highly accurate.
If a second plate of the layered structure is thick, the first aspect forms a loose hole through the second plate, the loose hole being larger than and substantially concentric with the pivot hole of the first plate. This loose hole may have lower accuracy, and therefore, it can be formed by etching. The first aspect may provide the second plate with a thickness appropriate for forming precision holes therethrough by etching and may form a precision pivot hole through the second plate by etching.
The precision pivot hole(s) is precisely fitted to and supported by a support of a carriage in a disk drive. The first aspect is capable of processing the at least two layered plates of the support plate means by etching, to improve the flatness of the support plate means.
A second aspect of the present invention forms the second plate with a resin layer and a metal layer and interposes the resin layer between the first plate and the metal layer, to provide a three-layer structure for the support plate means.
The second aspect employs the first plate as a main vibration system and the second plate as a supplementary vibration system involving the spring constant and attenuation of the resin layer and the mass of the metal layer, to improve the vibration characteristics of the head suspension as a whole. At the same time, the second aspect secures the effect of the first aspect.
A third aspect of the present invention forms a long base plate with the first and second plates.
The third aspect processes the first and second plates and pivot holes by etching, to improve the accuracy of the pivot holes. While securing the effects of the first and second aspects, the third aspect precisely fits the pivot holes to a support of a carriage so that the support of the carriage may correctly hold the head suspension. The third aspect also secures the flatness of the long base plate.
A fourth aspect of the present invention further has a resilient material for supporting the rigid part of the load beam with respect to the support plate means. A first end of the resilient material is laid on and fixed to an end of the rigid part, and a second end of the resilient material is laid on and fixed to an end of the long base plate.
While securing the effect of the third aspect, the fourth aspect forms a resilient part of the load beam from the resilient material that is separate from the rigid part of the load beam. The rigid part and resilient part can have their respective materials and thicknesses, to simultaneously realize requirements such as high rigidity for the rigid part and a low spring constant for the resilient part. The resilient part may be made of a precision material to provide a stable low spring constant.
The fourth aspect may make the rigid part thick to realize high rigidity without bends or ribs. This rigid part smooths air flows, suppresses the influence of turbulence due to the high-speed rotation of disks, and prevents the fluttering of the head suspension.
A fifth aspect of the present invention constitutes the load beam with the rigid part and a resilient part for resiliently supporting the rigid part with respect to the support plate means, and integrally makes the load beam from a single plate. The fifth aspect places an end of the load beam on an end of the long base plate of the third aspect and fixes it thereto.
While securing the effect of the third aspect, the fifth aspect simplifies the structure of the head suspension.
A sixth aspect of the present invention makes the first plate integral with the load beam and forms the second plate into a long base plate.
The sixth aspect processes the plates and pivot holes by etching, to improve the accuracy of the pivot holes and the flatness of the plates. While securing the effects of the first and second aspects, the sixth aspect improves the flatness of the first plate integral with the load beam and the second plate serving as a long base plate, and simplifies the manufacturing of the head suspension by integrally forming the first plate and load beam.
A seventh aspect of the present invention integrally provides the first plate with a resilient part for supporting the rigid part with respect to the support plate means. Also, the seventh aspect places an end of the load beam on an end of the resilient part and fixes it thereto.
The seventh aspect is capable of selecting proper material and thickness at least for the rigid part, to secure characteristics such as high rigidity required for the rigid part. The first plate integrally having the resilient part can be adjusted with respect to the second plate, to select material and thickness appropriate for the resilient part. This secures characteristics such as a low spring constant required for the resilient part. It is possible, therefore, to select materials and thicknesses appropriate for the rigid part and resilient part, respectively. It is easy for the seventh aspect to simultaneously satisfy the characteristics such as high rigidity required for the rigid part and the characteristics such as a low spring constant required for the resilient part. Since the resilient part is integral with the first plate of the support plate means, the seventh aspect simplifies the structure of the head suspension.